What would ever stop someone with ownership or access to an advanced telecommunications network (Verizon, for example) from setting up their own internet with their own extensions (.vzn, for example)?
That’s actually a sharp question.
The only thing stopping them is US law.
The federal government legally empowered ICANN to oversee each TLD — such as the one you mentioned: (.vzn)
So it really helps a Free Range ICANN if the president is a tryrant who hates freedom of speech. Such as Obama and especially Hillary:
On January 27, 1998 — ten days after Matt Drudge broke the Monica Lewinsky story — Hillary Clinton told reporters at a White House press conference that the Internet needed an “editing function or gatekeeping function”.
http://www.freerepublic.com/focus/news/1918104/posts
Nothing would stop the creation of a competing Domain Name Server by a major registry service like GoDaddy. It’s just a directory, something which maps a name (like FreeRepublic.com) to it’s IP address (the Internet equivalent of a phone number). Instead of resolving names against the ICANN directory, individual users can specify the GoDaddy directory.
ICANN can then get stuffed.